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Old 02-19-2008, 12:47 PM   #1
sloppydawg123
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Unhappy 1990 YZ250, White Smoke, Thick Transmission Oil

I have a 90 yz250, it has power, but had trouble idling. I cleaned the carb and everything, changed the oil. But it blows which smoke (radiator fluid i believe). Right now there is just water in the radiator. and it seems that one: it's getting into the chamber and being burned causing the white smoke, and two: is getting into the transmission oil, causing it to get that cloudy color and thick, which in time bogs on the clutch, so that it won't idle with he clutch in, only in neutral. Any ideas of fixes, or easy tests I can do to know? Maybe a dye in the radiator fluid?
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Old 02-19-2008, 12:52 PM   #2
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It's almost 20 years old. Get a manual. Pull the engine. Replace all the seals. Clean it up. Mike it out and replace anything out of tolerance.

Be thankful it's a 2 stroke. The rebuild won't cost much. A 4 stroke might cost thousands.
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Old 02-19-2008, 01:22 PM   #3
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Blown head gasket? That would allow the motor to suck the water in and blow out white smoke, as well as getting blowby into the bottom end.
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Old 02-19-2008, 01:37 PM   #4
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I figured as much as the head gasket or something so I planned on doing that, seems to be a pretty common problem. I was more concerned about the transmission oil thickening up, I put 30W-10 or something close to it in, but after a few rides it comes out like 140w, just really thick, and the bike won't idle, i think it's because of the pressure on the blutch, because it's fine right after new oil is put in
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Old 02-19-2008, 02:11 PM   #5
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Quote:
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Blown head gasket? That would allow the motor to suck the water in and blow out white smoke, as well as getting blowby into the bottom end.
But it wouldn't cause the tranny oil to thicken. Safest bet is to tear it down completely. Not hard on a single 2 popper. I've done enough of them.
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Old 02-19-2008, 04:23 PM   #6
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It's clearly a bad battery. I'd get one of the saturated glass mat replacements for it.
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Old 02-19-2008, 08:39 PM   #7
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Quote:
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It's clearly a bad battery. I'd get one of the saturated glass mat replacements for it.

No, it's obviously the clutch...the fluid thickens up because the 30w10 oil is mixing with the water and the resultant steam is causing the clutch plates to dissolve. That's why it gets thick, probably turn into oatmeal if you left it long enough.
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Old 02-19-2008, 09:11 PM   #8
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Thanks sarnali2, do you think a full rebuild of gaskets and seals will fix both problems?
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Old 02-19-2008, 09:12 PM   #9
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Quote:
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No, it's obviously the clutch...the fluid thickens up because the 30w10 oil is mixing with the water and the resultant steam is causing the clutch plates to dissolve. That's why it gets thick, probably turn into oatmeal if you left it long enough.
He'll try to get away cheap. And when it blows up a $300 rebuild job will become a $4000 new motorcycle.
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Old 02-19-2008, 09:16 PM   #10
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wait, what are you suggesting the solution is here?
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